Mount for electron discharge devices



Oct. 5, 1937. J. HIRMANN 2,094,654

MOUNT FOR ELECTRON DISCHARGE DEVICES v Filed June 2'7, 1936 INVENTOR JULIUS HIRMANN ATTORNEY Patented Oct.5,1937 2,094,554.

@UNITED STATES PATENT OFFICE MOUNT FOR ELECTRON DISCHARGE DEVICES Julius Hirmann, Hillside, N. J., assignor, by mesne assignments, to Radio Corporation of America, New York, N. Y., a'corporation of Delaware Application June 27, 1936, Serial No. 87,611

Claims. (01. 250-'-27.5)

My invention relates to improvements in elecand engaging the interior walls of the bulb withtron discharge devices and more particularly to out injury tothe mount during assembly or to the improved means for firmly and accurately posibulb during exhaust. Another object of my in,- tioning the electrode mount within the envelope vention is to provide such metallic spring spacers 5 of a tube. whichare simple to-manufacture and are easily. 5 In modern tubes, such as tubes having dome attached to the mount. type bulbs or envelopes, it is found'desirable to Thelnovel features which I believe to be char- 7 hold the electrode assembly firmly in place in the acteristic of my invention are set forth with parenvelope to prevent transverse movement of the ticularity in the appended claims, but the invenlQ mount. To this end the dome or other .contion itself will best be understood by reference to lo stricted portion of the tube is utilized to steady the following description taken in connection with the electrode assembly against transverse movethe accompanying drawing in which Figure 1 is a ment andto keep the assembly more firmly estabpartial view in perspective of one form of an lished in position than when the assembly is supelectron discharge device embodying my inven l5 ported and steadied only from the stem press. tion; Figure 2 is a horizontal cross section taken The mount should besteadied sufliciently to avoid along line 2-2 of Figure 1; Figure 3 is a side View noises, such as clicking, due to contact between of Figure 2; Figure 4 is a view in perspective of the electrode assembly and the envelope when the one of the spring spacers made according to my tube is jarred or vigorously vibrated. The steadyinvention before being applied to a mica spacer;

ingmeans or mount spacer should be sumciently Figure 5 is a partial view in perspective of a modi- 20 resilient to .avoid the stresses and distortion of fication of an electron discharge device embodythe mountassembly produced when a mount with I ing my invention; Figure 6 is a horizontal cross a rigid steadying means is forced into a bulb dome section taken along the line 6-6 of Figure, 5; smaller than usual. Metallic spring spacersare Figure? is a side view of Figure 6; Figure 8 is a resilient and easily made and. attached to the partial perspective view of another modification 25 mount, but the use of such metallic springs to of anelectron discharge device embodying my insteady the mount has not heretofore been favored vention; and Figure 9 is a partial perspective view becausestrain checks and cracks were often proof .a still further modification of an electron disduced inthe glass bulb during exhaust at the charge device'embodying my invention.

points where the metal touched the glass. It'is The electron discharge device shown in Figure 30 the usual practice to attach to the mount, the 1 has a dome type of bulb III, which is provided mica mount spacers either in the form ofa plate with the usual stem press and base not shown. or disc extending transversely of the dome por- The mount 'll comprises the usual electrode, astion' of the envelope or in'the form of vertical "sembly and extends into the tubular portion or oblong shaped micas attached to the mount interdome of the bulb Ill. The mount has secured to mediate their ends and with their ends in contact its upperfend by straps l2, welded to the mount, with the walls'of the bulb. Mica mount spacers a sheet insulator or electrode spacer I3, preferably also have some disadvantages, as commercial of mica; which may be of any shape, but is mica varies from .008 to .020 in thickness and shown as a disc-shaped plate in Figures 1, 2, and

q othe' resiliency of the mica mount spacers varies 3 and which extends transversely of the mount 40 considerably within the result that the mounts and of theitubular portion or dome of the, en"- are not always positioned centrallyof the bulb. velope l0.

Attaching the vertical micas to the mount is j Inview of the fact that the envelopes are not sometimes diificult and various ways of attaching all of exactlythe same diameter, rigid mount ;;5 the micahave been devised. Furthermore, mica spacers on the upper end of the mount to fit may split under stress and sometimes blisters snugly in the dome are not feasible. If the mount during the, high frequency heat treatment; A spacers are rigid and fit the largest envelope the metallic spring mount spacer or support would in amount will be. stressed and distorted when a many cases'bepreferable to amica spacer if it :smaller envelope is placed over the mount as 5 c could be used without harm to the bulb or to, the lsembly, while if the spacer fits the smaller en- R5 device by'metallic springs secured to the mount s'pacers' M in the form of bowed clips which are.

' tube, velope, it will be loose in the large envelopeand The principal object of .my invention isto hold clicking will result. firmly and accurately the free end of. an electrode In accordance With my invention I P v de t mountwithin the bulb of an electron discharge mica plate I3 with resilient metallic spring velope. a One form of spring spacer made according to my invention is best shown in Figure 4. 'The spacer M is provided at each end with a double loop or closely wound coil i5 providing a pair of spring clips between which the mica spacer can be separably engaged. The free ends may be, but need not be bent, as shown at it. When attached to a mica spacer and inserted in an envelope the fingers of the spring spacer take the position shown in the dotted lines. This arrangement provides a support having the resiliency of a coiled spring.

These metallic spring spacers, which may be made for example i tungsten, molybdenum or nichrome wire may be removably attached as best shown in Figures 2 and 3. These spring spacers are slipped over the edge of the mica plate 13, the plate being engagedbetween the turns of the coils i5, and the bowed outer ends engage the interior wall of the tubular portion of the en velope. When the bulb is'placed over the mount the spring fingers or ends ltare flexed inwardly toward'the of the tube to an extent dependent,

on the inner diameter of the dome of the bulb. These spring spacers resiliently center the mount from the. walls within the envelope and prevent clicking of the tube.

I have obtained very good results with nichrome wire of a diameter'of .016 (#26 B and S gauge) measuring about between the centers of'the coils [5, the diameter or" the coils being between .140 and .156". The distance from the center of the coil to the vertical portions at the end of the spring fingers measured .218", The length of the vertical portions of thefingers was .093". The mica was formed to provide a clearance of about .046 between the edge of the mica and the wall of the envelope, 'although'this dimension is not critical since the metallic spring spacer can be formed to take care of wide'variations.

While I donot wish to be restricted to any particular theory, I believethat the success of the metal spring fingers made in accordance with my invention is due to the "factthat they are of 'very small mass and do'not absorb very much heat and are heat insulated by means of the mica plate to'prevent conduction of heat to and from the mount. As the result the temperature of the spring fingers'is always so nearly the sameas the temperature of the envelope'that the temperature differential between the two is practically negligible, thus preventing'the checks and cracks in the glass envelope which are apt to occur when metallic spring spacers are used. A large temperature dii-Ierential is likely tofoccur when heat is rapidly conducted from the metallic spring mount spacers to the mount when heating the envelope, or'loy conducting heat to the spring spacers from the mount duringthe high frequency heat treatment ofthe mount. g Because the spring, spacer is-, easily made and easilyapplied, manufacturing is simplified, there being no need to thread the wire spacer through apertures in the mica or to provide extra means for fastening the metal spring spacers to the mica spacer. This reduces the timerequired forassembly of the mount. A metal spring spacer 'made according to my invention has more resiliency'than'othertypes' of spacers, metal or otherwise, and hence is capable of taking care of wider variations of bulb diameter.

In a modification shown in Figures 5, 6, and 7 the mica plate 2% has spaced around it, near its edge, slots 28 through which the metallic spring spacers extend, the mount spacers being formed. as 'best shown in Figure 6 to provide a central portion 23 engaging the underside of 'mica spacer Z Qand folded reverse portions 24 engaging the upper surface of the mica spacer 20 to form clips to attach the spring spacers to the mica. Free ended bowed portions or fingers 25 resiliently engage the inner wall of the dome portion of the envelope of the tube.

In the modification shown in Figure 8 the mica plate 26 is provided with slots 2'1 into which the metallic spring element 28 having spring clips 29 'is inserted to position the spring. The spring is clipped to the mica to secure it to the mica 26 by clips El-l so that its ends til extend beyond the edges of the'inica and contact the interior walls of the tubular portion of the envelope to space the mount within this portion of the envelope.

As shown in the modification in Figure 9 the mica plate 36 may be provided with slots 32 into which portions of the metallic spring elements extend. The spring spacer is provided with a central portion 33 having bent portions 34 engaging the lower surface of the mica plate 3i and reversely bent portions 3%; engaging the upper surface of the mica plate'3 i these reversely bent portions forming a pair of clips so that the mica plate is clipped between the reversely bent portions Stand 35. The free ends 36 of the springs extend over the edges of the mica and into contact with the wall of the bulb.

These metallic spring spacers are capable of providing for wider variations of bulb diameters than the usual type of mica spacer and are usually more easily made and attached to the mount and retain their resiliency duringthe sealing and high frequency treatment of the mount-during the exhaustoperation.

'While I-"have indicated the" preferred embodiments of my invention of which I am now aware and have" also indicated only one specific application for which my invention may be employed,

it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is'employed without departing fromfthe scope of my invention as set forth in the appended claims.

What'I claim as new is,-

v 1. An electron discharge device comprising an envelopehaving a tubular portion, a mount enclosed bysaid envelope and comprising an electrode assembly positioned to extend into the tubular portion of the envelope and having a plate of insulating material secured to the end of the mount to extend transversely of the tubular portion 'of.thebulb,'and metallic spring spacers provided intermediate their ends'with 'a spring clip for separably'engag'ing the edge of said plate .w'ithrtheir ends extending beyond the edges of said plate and engaging the walls of the tubular portion of the envelope 'to resiliently sup-port the mount within the tubular portion of the envelope.

2. An electron discharge device comprising an envelope having a tubular portion, amount enclosed by said envelope and comprising an electrode assembly positioned to be at least partially within said tubular portion, a sheet insulator se" cured to said mount to extend transversely of the tubular portion of said envelope, and metallic spring spacers provided intermediate their ends with a pair of spring clips for engaging the edge of the sheet insulator, said springs having their ends in contact with the Walls of the tubular portion of said envelope to resiliently steady said mount from the walls of the tubular portion of said envelope.

3. An electron discharge device comprising an envelope having a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly positioned to extend into said tubular portion, a mica plate secured to the end of the mount to extend transversely of the tubular portion of the envelope, vand metallic spring spacers provided intermediate their ends with a pair of closely Wound coils providing spring clips for engaging the edge of said mica plate with their free ends in contact with the walls of the tubular portion of the envelope to resiliently steady the mount from the walls of the tubular portion of said envelope.

4. An'electron discharge device comprising an envelope having a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly positioned to be at least partially Within said tubular portion, a mica plate secured to the mount to extend transversely of the tubular portion of the envelope, slots in the edges of said mica plate and metallic spring spacers extended into said slots and having a pair of spring clips for engaging the edge of the mica plate adjacent the slots and having its ends extending beyond the edges of said mica plate to contact the walls of the tubular portion of the envelope to resiliently steady the mount within the tubular portion of the envelope.

5. An electron discharge device including an envelope having a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly positioned to extend into the tubular portion, a mica plate secured to the mount to extend transversely of the tubular portion of the envelope, slots in the edges of said mica plate, metallic spring elements positioned within said slots and having two pairs of reversely bent portions disposed on opposite sides of said plate for engaging said mica plate between said reversely bent portions to secure said metallic spring elements to said mica plate with the ends of said spring elements extending beyond the edges of said mica plate to contact the walls of the tubular portion of the envelope to resiliently steady the mount within the tubular portion of the envelope.

JULIUS HIRMANN, 

